1. Technical Field
The present invention relates to an exposure head for making an image by using lights from light emitting elements through an image forming optical system and an image forming apparatus using the same.
2. Related Art
JP-A-2009-098613 discloses an exposure head including a plurality of light emitting elements arranged in a zigzag manner in the main scanning direction, and an image forming optical system facing the plurality of light emitting elements. That is, in the exposure head, by making an image by using a plurality of lights emitted from the light emitting elements through the image forming optical system, spots of the plurality of lights are arranged in the main scanning direction and the plurality of lights are irradiated onto a surface to be exposed. Then, the surface to be exposed is exposed by the spots.
As described above, the exposure head exposes the surface to be exposed by the plurality of spots arranged in the main scanning direction. Thus, in order to realize exposure with high accuracy, it is necessary to form each spot such that various conditions are satisfied. Among the conditions, it is most important to reduce aberration of the image forming optical system and sufficiently ensure the amount of lights supplied for spot formation. For compatibility of these two conditions, the magnification in the main scanning direction of the image forming optical system serves as an important parameter. That is, if the magnification in the main scanning direction is large, the aberration is increased. Meanwhile, if the magnification in the main scanning direction is small, light use efficiency is reduced, so that the amount of lights supplied for spot formation is reduced. However, these points have not been sufficiently considered in the related art.